XRT72L50 Datasheet, PDF (350/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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Enabling and Disabling the Detection of Framing Error Interrupt
The user can enable or disable the Detection of Framing Error’ interrupt by writing the appropriate value into Bit
1 (Framing Error Interrupt Enable) within the Rx E3 Interrupt Enable Register - 2, as indicated below.
RxE3 Interrupt Enable Register - 2 (Address = 0x13)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
FERF
Interrupt
Enable
BIP-4 Error Framing Error
Interrupt
Interrupt
Enable
Enable
Not Used
R/W
RO
RO
RO
R/W
R/W
R/W
RO
0
0
0
0
0
0
X
0
Setting this bit-field to “1” enables this interrupt. Conversely, setting this bit-field to “0” disables this interrupt.
Servicing the Detection of Framing Error Interrupt
Whenever the XRT72L50 Framer IC detects this interrupt, it will do the following.
• It will assert the Interrupt Request output pin (Int), by driving it "High".
• It will set the Bit 1 (Framing Error Interrupt Status), within the RxE3 Interrupt Status Register - 2 as indicated
below.
RxE3 Interrupt Status Register - 2 (Address = 0x15)
BIT 7
RO
0
BIT 6
BIT 5
Not Used
RO
RO
0
0
BIT 4
RO
0
BIT 3
FERF
Interrupt
Status
RUR
0
BIT 2
BIP-4
Error
Interrupt
Status
RUR
0
BIT 1
Framing
Error
Interrupt
Status
RUR
1
BIT 0
Not Used
RUR
0
Whenever the Terminal Equipment encounters the Detection of Framing Error Interrupt, it should do the
following.
• It should read the contents of the PMON Framing Bit/Byte Error Count Registers (located at Addresses 0x52
and 0x53) in order to determine the number of Framing errors that have been received by the XRT72L50
Framer IC.
5.3.6.2.9
The Receipt of New LAPD Message Interrupt
If the Receive LAPD Message Interrupt is enabled, then the XRT72L50 Framer IC will generate an interrupt
anytime the Receive HDLC Controller block has received a new LAPD Message frame from the Remote
Terminal Equipment, and has stored the contents of this message into the Receive LAPD Message buffer.
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